Category: tools

I love my Netscout AirCheck G2, and I’ve mentioned before that one of my favorite features is the wired Ethernet test. It’s so much easier to plug the AirCheck into a port on a wall and have it tell me which switch and interface that port is patched to than tracking a MAC address in a terminal session.

I like the Ethernet test on my AirCheck G2 enough that I’ve been thinking about picking up a Netscout LinkRunner AT to have a dedicated Ethernet/Fiber tester. Thank goodness I didn’t, because I would have been cursing at my terrible timing instead of cursing at the badassedness (this will be a real word one day, just you wait) of the new Netscout LinkRunner G2.

Twinsies!

I was very fortunate to have an opportunity to take the new LinkRunner G2 for a test drive, just weeks before its public debut, and I can tell you that Netscout has packed a lot of improvements into this unit. At a glance, it looks identical to the AirCheck G2 – the two units sport the same chassis. I’m going to make a lot of comparisons to the AirCheck G2, and really none to the previous version of the LinkRunner – I’ve never owned that unit; and really, I think it’s more useful to understand how the two tools differ and overlap.

The LRG2 Home Screen

In contrast to the AirCheck’s customized Linux firmware, the LinkRunner G2 runs Android, and that enables a whole snowball of cool enhancements.

As a network engineer, if I had a smartphone with an SFP slot on it and the Netscout LinkRunner software, I’d have the best tool ever in my pocket, and that’s pretty much what Netscout has done. There is a camera for taking pictures of switches, patch panels, and the copper wiring that you just found that has clearly been some raccoon’s lunch. It also has an LED flashlight for confirming that, yep, the raccoon is living in that hole in the corner (don’t tell me you’ve never run into a data center raccoon… they’re very common in the great white north!), or just tracing cables over ceiling tiles. You can also install your email client on it and, with the optional Wi-Fi/BT/BLE adapter, send those pictures immediately to your manager so they can find out who is responsible for sending pest control. Uh oh, you’re going to have to deal with the critter yourself? Well open up the chrome browser and you can google “nearest pest control”, and then you can watch YouTube while you wait. Nifty.

As a network tool specifically, LinkRunner G2 is all about diagnosing problems on the wire – you won’t be splicing or fusing fiber with this guy, but it will tell you beyond a doubt if you can blame your problems on that wiring. There are three main test pages: SWITCH, AUTOTEST, and CABLE.

The SWITCH page will show you the CDP or LLDP information of the switch the unit is plugged into, the speed and duplex, and PoE info including the voltage and wattage, and which pins are carrying current. From here you can also flash the LEDs on the switch port, with a configurable interval.

There’s also an SFP slot on the unit, so we can do some fiberoptic testing as well. I was initially a little freaked out by the LED behaviour though – have you ever seen an empty copper port with the LEDs on?!? That’s the start of a networking scary movie right there.

“Can I borrow your status LEDs?”

If the unit is plugged into a fiberoptic patch cable with an SFP module in the slot, it can also display the module temperature, and Tx/Rx levels.

Connected Switch and Fiberoptic SFP info

The AutoTest

The AUTOTEST page operates very similarly to the Ethernet Test and AutoTest on the Aircheck G2, with some enhancements. Like the AirCheck G2, The LRG2 displays whether PoE is detected, the link speed and duplex, CDP or LLDP info, DHCP lease details, DNS server assignment, default gateway reachability, and uploads the results to Link-Live – Netscout’s online repository of all of your test information. With Link-Live (included free with either device), all of your testing history is accessible in one place.

PoE Info

Link Info

CDP or LLDP Info

DHCP Info

DNS Info

Default Gateway Reachability

Configurable Target Reachability

Continuous Ping to Target

But the LRG2 takes many of these tests to another level:

The LRG2 can be configured to request whatever class of PoE you choose – right up to UPOE (25.6 – 51.0 Watts, roughly).

The TruePower feature can actually load the line; drawing power to tell you the actual wattage and voltage used, which can help point out issues with your switch or the cable.

This is a big one! The LRG2 allows you to set a VLAN tag and priority. Now you can test actual data transfer on trunk ports and even get a sense of QoS treatment if those ports are congested.

The delta of the time from the DHCP discover to offer is reported, as well as the delta from the request to the acknowledgment; and the lease length.

There is now the ability to have the LRG2 run a continuous TCP ping to a configurable target (google.com port 80, by default).

Pictures and comments can be added to the test results directly from the LRG2 AUTOTEST page – and since there’s a built-in camera, this is really easy to do.

Wired 802.1X authentication, IPv6, and proxy configuration

Set a user-defined MAC address for the LRG2 unit. Much easier to find 00:11:FE:ED:FA:CE in those bridge-tables!

Add Pics and Notes right from the AutoTest screen

Red means not good 😦

Ooooh! This makes me happy!

So Netscout has really squeezed in some good stuff here. Next, let’s take a look at the physical cable testing:

This is what you want to see…

When plugged into an Ethernet cable where the far side is unterminated or unplugged, the LRG2 uses TDR to draw out each conductor, points out the estimated cable length (+/- about 1ft) and indicates if there are any breaks (open conductors), split pairs, etc. Here’s one of the Cat5 cables that the previous owner of my house ran out to the garage, but I’ve never been able to get gigabit speeds over:

This is what happens when someone thinks it’s clever to use a single Ethernet cable to terminate both a voice and a data jack.

Well that explains that. There are some accuracy improvements over TDR to be had by using the included wiremap #1 termination (wiremaps #2-5 are available from Netscout). TDR actually tests per pair, so it can only tell you if there is a problem within that conductor pair. The wiremap allows testing each individual pin.

Without the wiremap, test shows an open pair

With the wiremap, the test is able to determine the specific open pin

By pressing the purple + sign on this page, there are options to send 3 types of tone over the cable so you can use your favorite toning equipment to run around the building looking like you’re dowsing for water while finding out just where that cable really goes. A useful feature regardless of how you look taking advantage of it.

But wait there’s more…

There’s still plenty to talk about here. With the Android OS, the LRG2 gets fast sleep/wake functionality. Just tap the power button to sleep or wake the unit. This helps balance battery drain without having to wait for the unit to restart every time you bring it out of your tool bag. Which is important – because Android can be battery intensive; the LRG2 data sheet says to expect a 4 hour battery life, which is… not much.

Charging via PoE

The good news is that the unit also charges over PoE! But only when the unit is fully powered. So plan to be conscious of your battery life in the field.

There are two big usability features that the LRG2 has that I wish would come over to the Aircheck G2; the first of which are over-the-air updates. Just like your Android smartphone, you can go to the settings menu and check for updates. The unit can then download the update over the Ethernet (though I guess that wouldn’t really be over the “air”)or Wi-Fi connection and install it on the unit. No laptop required.

The second feature is removable micro SD storage. The AirCheck G2 can dump screenshots and session files to a USB drive, but the LRG2 can actually browse the SD card, and files can be copied or organized on the drive right from the File Manager application on the unit. It’s clear to see that Netscout has really focused on enabling more efficient workflows for technicians using this device, looking back at things like the ability to add screenshots and comments right from the testing page. With the Android OS, you can even install your favorite email client on the unit and get your trouble tickets sent directly to the device.

There are a couple of points to note here – the USB Wi-Fi adapter is useful to enable network access on the go. It’s not included in the base bundle, but you could also use a wired connection in that case. In addition, the unit does not have full access to the Android app store. One of the bullet points Netscout is advertising here is the elimination of the security risk of using personal devices… and allowing open access to the app store would make that a debatable point. Instead, Netscout is whitelisting certain apps like Speedtest, iPerf apps, and vendor specific configuration utilities, which are then made available on a Link-Live version of the store. Netscout says for now that users will be able to send a request to Netscout to have an app added to the store if there is a particular one they feel is missing, and there are plenty of useful apps available already.

Speedtest App – over Wi-Fi

So now I’m trying to decide if I can justify the expense of a new LRG2 for my work (yes, they’re making me send the review unit back 😩). At roughly $3000 USD, the unit isn’t a small expense. For me personally, I think the AirCheck G2 covers my use cases more completely, having both advanced wireless testing capabilities and enough wired testing ability for most wireless and even route/switch engineers to determine if they need to call the electrician or cabler (by contrast, the LRG2 Wi-Fi adapter only enables the unit to find a network connection – there is no ability to test over the wireless connection… as of today). It was also tough to justify spending approximately $2500 USD on the AirCheck G2 at the time. That being said, the Netscout team just delivered some BIG enhancements to the AirCheck G2 and I feel like that has made it a great purchase. Knowing how hard the Netscout teams have been working on these devices (look at all of the enhancements today at initial release) and with the LRG2 running on Android, I would make a big bet that we’re going to see a lot of feature additions to this unit soon enough.

Now if the teams at Netscout could just slap together an AirLinkCheckRunner G2 in the same size and form factor, I’d be smitten. I’ll be fair though – there is most likely a broader audience than network engineers like me for the LRG2 in technicians and installers that need simple test results for a large number of cable drops in a short period of time – and this unit is really going to work well for those teams. I’d love to see the cablers that I work with carrying one of these around.

iPerf performance testing. (!!!!!) Not only can you now check upstream and downstream throughput against an iPerf server, there’s even a slick new accessory so you don’t have to build your own iPerf box. I’ve been using this on projects and it’s a great way to check only the links you really want to – rather than pulling out speedtest.net on my iPhone where I can’t tell if the internet link is the bottleneck. The accessory looks just like a darker coloured LinkSprinter and can run on PoE (or a couple of AAs), and has a basic web server. Hot damn.

Captive Portal Support. Another big feature, this has made my G2 fully functional where it used to have a fatal weakness – captive portals would render it useless for active association testing. Now the built-in browser makes it possible to fully enter authentication credentials or accept a AUP. Brilliant.

ACL / Authorization classes. This is really AP categorization. Set a big ‘ol flag on that unauthorized AP so you know it’s, well, unauthorized. The G2 will also flag rogues detected on the auto test. Could be handy.

Interferer Identification. I relate this to Cisco’s clean air. The G2 can now detect things like Bluetooth devices, Microwaves, and other sources of interference. The G2 shows duty cycle and which channels are affected. This is not full spectrum analysis, but meet your new handheld interference locator. Shut the front door.

Interferer Types 1

Interferer Types 2

Packet Capture. Save your session file and now optionally add a PCAP of all the testing you did; then take it away for offline analysis. Includes radio tap headers. Yes please.

Channel Overlap View. Another way of visualizing where all of those APs are camped out, in a view we’re all familiar with these days. From the channels menu, find the overlap button in the bottom left corner to get to the new view. from there, you can tap on any of the parabolic arcs to get an expanded view of the AP BSSIDs that are on that channel.

Phew. Let’s take a break right there. That’s a LOT of big features that just got jammed into our handy little tool. Way to go Netscout on adding value to the platform!

If you have MasterCare support for your AirCheck G2, download firmware version 2.0.0 from this link.

You can also find a technical overview from Netscout here, and a recent webinar where Netscout talks with George Stefanick with Houston Methodist hospital about how they’re using the new Aircheck G2 features here.